Cyanine bases containing an azaindenyl nucleus



United States Patent ice CYANINE BASES CONTAINING AN AZAINDENYL NUCLEUS Frank G. Webster, Donald W. Heseltine, and Leslie G. S. Broolrer, Rochester, N .Y., assiguors to Eastman Kodak fompany, Rochester, N.Y., a corporation of New ersey No Drawing. Application July 15, 1957 Serial No. 671,723

6 Claims. (Cl. 260-240) This invention relates to new cyanine bases containing an azaindenyl nucleus which are useful in spectrally sensitizing photographic silver halide emulsions.

This application is a continuation-in-part of application Serial No. 607,236, filed August 30, 1956.

The new cyanine dye bases of our invention can advantageously be represented by the general formula wherein R represents a lower alkyl group, such as methyl, ethyl, etc. (e.g., an alkyl group containing from 1 to 2 carbon atoms), R represents a tetrazaindenyl group or a pentazaindenyl group, d represents a positive integer of from 1 to 3 and Z represents the non-metallic atoms necessary to complete a benzothiazole nucleus or a benzoxazole nucleus. The benzene ring of the heterocyclic nucleus defined \by Z can contain simple substituents, such as chloro, bromo, methyl, ethyl, methoxyl, ethoxyl, phenyl, etc.

Included among the dyes represented by Formula I above, are the dyes represented by the following general formula:

Ia. x

wherein R, R and d each have the values given above and X represents an oxygen atom or a sulfur atom.

It is, therefore, an object of our invention to provide new cyanine bases containing an azaindenyl nucleus. Another object is to provide a method of making these cyanine bases. Still another object is to provide photographic silver halide emulsions sensitized with the new cyanine bases of our invention and a method of preparing such sensitized photographic silver halide emulsions. Other objects Will become apparent from a consideration of the following description and examples.

By the term pentazaindenyl group we mean the group represented by the following formula:

wherein R represents a hydrogen atom or a methyl group. By the term tetrazaindenyl group we mean the group represented by the following formula: CH3

According to our invention, we provide the new cyanine bases of Formula I above by reacting together a cyclammonium quaternary salt selected from those represented by the following general formula:

wherein R and Z each have the values given above, X; represents an acid radical (e.g., chloride, bromide, iodide,

\ thiocyanate, sulfamate, methylsulfate, ethylsulfate, per

chlorate, benzenesulfonate, p-toluenesulfonate, etc.) and D represents an alkylthio group (e.g., methylthio, ethylthio, etc.), an arylthio group (e.g., phenylthio, tolylthio, etc.), a fl-acylarylaminovinyl group (e.g., p-acetanilidovinyl, p-propionylanilidovinyl, etc.), or a 4-acylarylamino-1,3-butadienyl group (e.g., 4-acetanilido-1,3-butadienyl, 4-propionylanilido-1,S-butadienyl, etc.), with a compound represented by the following general formula:

wherein R, has the values given above, or the compound represented by thefollowing formula:

N mo k The condensations of our invention can advantageously be accelerated by heating the reaction mixture, generally temperatures varying from ambient temperature (ca. 20 C.) to the reflux temperature of the reaction mixture being satisfactory. The condensations can be carried out in the presence of an inert solvent, such as pyridine, nitrobenzene, ethanol, n-propanol, isopropanol, nbutanol, etc.

The condensations of our invention can also be carried out in the presence of a basic condensing agent, such as the trialkylamines (e.g., triethylamine, tri-n-propylamine, triisopropylamine, tri-n-butylamine, triisobutylamine, trin-amylamine, etc.), N-alkylpiperidines (e.g., N-methylpiperidine, N-ethylpiperidine, etc.), N,N-dialkylanilines (e.g., N,N-dimethylaniline, N,N-diethylaniline, etc.), etc.

The following examples will serve to illustrate more fully the manner of preparing the cyanine bases of our A mixture of 1.35 g. (1 mol.) of S-methyltetrazoloialpyrimidine, 3.67 g. (1 mol.) of 3-methyl-2-methylmercaptobenzothiazolium p-toluene sulfonate, 1.0 g. (1 mol.)

of triethylamine and 15 ml. of pyridine was heated at the refluxing temperature for 10 minutes. The reaction mixture was stirred in ml. of methanol, and after chilling the solid was collected on a filter and washed with methanol. The dye was dissolved in hot pyridine, the solution was filtered, methanol was added, and after Patented May 19, 9.

2.-5- (3-ethyl-2 (3H) benzothiazolylidene) propenyl] -tetrazl0 [a] pyrimidine Example A mixture of 1.35 g. (1 mol.) of-methyltetrazololalpyrimidine, 4.5 g. (1 mol.) of 2-(2-acetanilidovinyl)-3- ethylbenzothiazolium iodide, 1.0 g. (1 mol.) of triethylamine and 15 ml. of pyridine was heated at the refluxing temperature for 5 minutes. The reaction mixture was stirred in 150 ml. of methanol, after chilling the solid was collected on a filter and washed with methanol. The dye was dissolved in pyridine, the solution was filtered, methanol Was added, and after chilling the dye was collected on a filter and washed with methanol. After another such purification the yield of dye was 47%. The very dark purplish mat had a M.P. of 187- 188 C. with decomposition and it sensitized a photographic gelatino-silver-bromoiodide emulsion to about 685 m with maximum sensitivity at about 580 mp and about 670 mp.

3.-5- (3-ethyl 2 (3H) benzoxazolylidene) propenyl] -tetraz0l0 [a] pyrimidine A mixture of 1.35 g. (1 mol.) of 5-methyltetrazolo[a]- pyrimidine, 4.34 g. (1 mol.) of 2-(2-acetanilidovinyl)-3- ethylbenzoxazolium iodide, 1.0 g. (1 mol.) of triethylamine and 20 ml. of pyridine was heated at the refluxing temperature for minutes. The reaction mixture was stirred in 150 ml. of 90% aqueous methanol. After chilling the solid was collected on a filter and washed with a small quantity of cold methanol. The dye was dissolved in hot pyridine, the solution was filtered, methanol was added, and after chilling the dye was collected on a filter and washed with methanol. After another such purification the yield of dye was 23%. The dark blue crystals had a M.P. of 204-205 C. with decomposition and they sensitized a photographic gelatinosilver-bromoiodide emulsion to about 630 m with maximum sensitivity at about 570 mp.

Example 4.5- (3-ethyl-2 (3H) -benzothiazolylidene)1,3- pentadienyl] tetrazolo [a] pyrimidine gHy A mixture of 1.35 g, (1 mol.) of 5-methyltetrazolo[alpyrimidine, 4.76. g. (1 mol.) of 2-(4-acetanilido-l,3- hutadienyl)-3-ethylbenzothiazolium iodide and 20 ml. of pyridine was heated. at the refluxing temperature for 5 minutes. The reaction mixture was stirred in 200 ml.

Example Example 5 .5 (3-ethyl-2 (3H benzoxazolylidene) propenyl] -7-methyl-s-triazalo [2,3-a] pyrimidine N gHr A mixture of 13.02 g (1 mol.) of Z-fi-acetanilidovinyl- 3-ethylbenzoxazolium iodide, 4.44 g. (1 mol.) of 5,7- dimethyl-s-triazolo[2,3-alpyrimidine, 50 ml. of absolute ethyl alcohol and 8.08 g. (1 mol. plus 100% excess) of triethylamine was heated at the reflux temperature for 45 minutes. The cool reaction mixture was stirred with cold water and the whole chilled. The product was collected on a filter and washed with water. The yield of dye was 4% crude and 2% after two recrystallizations from methyl alcohol. The dull red crystals had M.P. 212-213 C. with decomposition, and they sensitized a photographic gelatino-silver-bromoiodide emulsion with maximum sensitivity at about 520 m Example 6.-5- (3-ethyl 2 (3H) benzothz'azolylidene)- propenyl] -7-methyl-s-triazolo [2,3-a] pyrimidine N ha.

A mixture of 4.5 g. (1 mol) of 2-p-acetanilidovinyl- 3-ethylbenzothiazolium iodide, 1.48 g. (1 mol.) of 5,7- dimethyl-s-triazolo[2,3-alpyrimidine, 20 ml. of absolute ethyl alcohol and 2.02 g. (1 mol. plus excess) of triethylamine was heated at the reflux temperature for 35 minutes. The cool reaction mixture was stirred with cold water and the whole chilled. The product was collected on a filter and washed with methyl alcohol. The yield of dye was 20% crude and 9% after two recrystallizations from methyl alcohol. The brown needles with a blue reflex had M.P. 242-244 C. with decomposition, and they sensitized a photographic gelatino-silver-bromo iodide emulsion with maximum sensitivity at about 570 mp.

Example 7.5 (3 -ethyl-2 (3H -benz0thiazolylidene) propenyl] -7-methyyltetraz0lo [a] pyrimidine 5,7-dimethyltetrazolo[alpyrimidine (1.49 g., 1 mol.), ZB-acetanilidovinyl-Ii-ethylbenzothiazolium iodide (4.50 g., 1 mol.) and triethylamine (1.5 ml., 1 mol+10%) were dissolved in ethyl alcohol (15 ml.) and heated under reflux for thirty minutes. After chilling, the crude dye was thrown out of solution by the addition'with stirring of water. The aqueous portion was decanted and the residue dissolved in acetone and again precipitated with water. The solid was filtered off and extracted with boiling benzene. The benzene solution of the dye was filtered, concentrated and chilled. The crude dye was then filtered off and dried. After two recrystallizations from ethyl alcohol, the yield of pure dye was 0.20 g. (6%), M.P. 190-191 C. dec.

Analysis, calcd. for C17H16N6S: N, 25.0%. Found: N, 24

As shown in the above examples, the cyanine bases of our invention are particularly useful in manufacturing photographic silver halide emulsions, serving to alter the sensitivity thereof. Sensitization by means of our new bases is, of course, directed primarily to the ordinarily employed, gelatino-silver-halide, developing-out emulsions. The bases are advantageously incorporated in the washed, finished emulsion and should, of course, be uniformly distributed throughout the emulsion. In the preparation of photographic emulsions containing our new bases, it is only necessary to disperse the bases in the emulsions. The methods of incorporating bases in emulsions are simple and well known to those skilled in the art of emulsion making. It is convenient to add the bases from solutions in appropriate solvents. The solvent must, of course, be compatible with the emulsion and substantially free from any deleterious effect on the lightsensitive materials. Pyridine (or warm methanol) has proven satisfactory as a solvent for the majority of our new bases.

The concentration of our new bases, in the emulsion can vary widely, i.e.', from about to about 100 mgs. per liter of flowable emulsion. The concentration of the base will vary according to the type of light-sensitive material in theemulsion and according to the efiects desired. The suitable and most economical concentration for any given emulsion will be apparent to those skilled in the art upon making the ordinary tests and observations customarily used in the art of emulsion making.

To prepare a gelatino-silver-halide emulsion sensitized with one of our new bases, the following procedure is satisfactory: A quantity of the base is dissolved in pyrisensitizers, e. g., sulfur sensitizers (e.g., allyl thiocarbamide, thiourea, allylisothiocyanate, cystine, etc.), various gold compounds (e.g., potassium chloroaurate, auric trichloride, etc.) (see'U.S. Patents 2,540,085; 2,597,856 and 2,597,915), various palladium compounds, such as palladium chloride (U.S. 2,540,086), potassium chloropalladate (US. 2,598,079), etc., or mixtures of such sensitizers; anti-foggants, such as ammonium chloroplatinate (US. 2,566,245), ammonium chloroplatinite (US. 2,566,263), benzotriazole, nitrobenzimidazole, S-nitroindazole, benzidine, mercaptans, etc. (see Mees-The Theory of the Photographic Process, Macmillan Pub., page 460), or mixtures thereof; hardeners, such as formaldehyde (US. 1,763,533), chrome alum (US. 1,763,- 533), glyoxal (US. 1,870,354), dibromacrolein (Br. 406,- 750), etc.; color couplers, such as those described in US. Patent 2,423,730, Spence and Carroll US. Patent 2,640,- 776, etc.; or mixtures of such addenda. Dispersing agents for color couplers, such as those set forth in US. Patents 2,322,027 and 2,304,940, can also be employed in the above-described emulsions.

The cyanine bases of our invention represented by- Formula I above can be quaternated by heating with an alkyl salt, such as ethyl-p-toluenesulfonate, to provide cyanine dyes. However, we have found that several dyes prepared in this manner, and in particular the dyes containing a tetrazaindenyl nucleus, do not have as useful a sensitizing action as the corresponding cyanine bases. In several instances, this difference is quite marked. Dyes corresponding to the cyanine bases of Formulas I or II above, wherein R represents a tetrazaindenyl group have been previously described in US. Patents 2,439,210, dated April 6, 1948 and 2,443,136, dated June 8, 1948.

. As indicated above, the cyanine bases have considerably dine or other suitable solvent and a volume of this solution (which may be diluted with methanol) containing from 5 to 100 mgs. of base is slowly added to about 1000 cc. of a gelatino-silver-halide emulsion, with stirring. Stirring is continued until the base is uniformly distributed throughout the emulsion. With most of our new bases, 10 to 20 mgs. of dye per liter of emulsion suffices to produce the maximum sensitizing effect with the ordinary gelatino-silver-bromide (including bromiodide) emulsions. With fine-grain emulsions, which include most of the ordinarily employed gelatino-silver-chloride emulsions, somewhat larger concentrations of base may be necessary to secure the optimum sensitizing eifect.

The above statements are only illustrative and are not to be understood as limiting our invention in any sense, as it will be apparent that our new bases can be incorporated by other methods in many of the photographic silver halide emulsions customarily employed in the art. For instance, the bases can be incorporated by bathing a plate or film upon which an emulsion has been coated, in the solution of the base, in an appropriate solvent. Bathing methods, however, are not to be preferred ordinarily.

Photographic silver halide emulsions which can advantageously be sensitized by means of the new bases of our invention comprise the customarily employed gelatino-silver-chloride, gelatino-silver-chlorobromide, gelatino-silver-bromide, and gelatino-silver-bromiodide developing-out emulsions.

Photographic silver halide emulsions, such as those listed above, containing the sensitizing dye bases of our invention can also contain such addenda as chemical higher speeds than the corresponding dyes.

The following examples will serve to illustrate the method of preparing certain of the azaindenyl intermediates useful in practicing our invention.

Example 8. 5,7-dimethyltetrazolo [a] pyrimidine i CH: N T

Example 9.5-methyltetraz0lo[a] pyrimidine or 6- methyl-1,2,3,3a,7-pentazainden'e A mixture of 15.5 g. of 4,4-dimethoxy-2-butanone and 8.6 g. of S-aminotetrazole in a solution of ml. of xylene and 15 ml. of N,N-dimethylformamide was heated under a suitable fractionating column, and the methanolwater distillate was removed as formed. The reaction was continued until no more distillate came over, and the resulting solution was treated with decolorizing carbon and filtered. A 76% yield of the desired pentazaindene compound was obtained. Recrystallization of the product from ethanol produced nearly colorless crystals having a melting point of 134 C.

Calcd. for C H N C, 44.4; H, 3.7; N, 51.8. Found:

76 C, 44.5; H, 3.4; N, 51.3.

What we claim as our invention and desire secured by Letters Patent of the United States is:

1. A cyanine base selected from the group consisting of those represented by the following two general formulas:

wherein R represents a lower alkyl group, R represents a member selected from the group consisting of a hydrogen atom and a methyl group, Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of a benzoxazole nucleus and a benzothiazole nucleus, and d represents a positive integer from from 1 to 3.

2. The cyanine base represented by the following formula:

3. The cyanine base represented by the following formula:

N /C=CH-CH=CH \N S '4. The cyanine base represented by the following formula:

N 6 g o\ 1 \CH /o=on-on=on \N N/ 5. The cyanine base represented by the following formula:

on. N

N \CH /o=on-on=on XN/ N UNITED STATES PATENT OFFICE Certificate of Correction Patent No. 2,887,480 May 19, 1959 Frank G. Webster et a1.

It ishereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 21, after by the insert -foll0wing; column 4:, line 61, heading of Example 7 for -methyyltetmz0lo[a] pyrimidine read -methyltetmeolo [w]pyrimidz'ne; column 5, line 11, for the indistinct matter read N, 24.7%.-; colunm 7, line 25, for from, first occurrence, read of-; column 8, lines 14 to 22 inclusive, the formula should appear as shown below instead of as in the patent:

02: 5 Signed and sealed this 20th day of October 1959.

[SEAL] Attest: KARL H. AXLINE, ROBERT C. WATSON, Attesti ng Oyfiaer. Gonwnissz'oner of Patents. 

1. A CYANINE BASE SELECTED FROM THE GROUP CONSISTING OF THOSE REPRESENTED BY THE FOLLOWING TWO GENERAL FORMULAS:
 6. THE CYANINE BASE REPRESENTED BY THE FOLLOWING FORMULA: 